1. Field of the Invention
The present invention relates to in-mold transfer films, and more particularly to an in-mold transfer film suitable for multi-kind and small-quantity production.
2. Description of the Related Art
In known in-mold decorating, a printed in-mold transfer film (sheet) is arranged in a mold used for injection molding, so that a molded part as a transferred object is formed by injection molding, and at the same time, various images such as patterns or characters are transferred on a surface of the molded part in the mold.
Japanese Unexamined Patent Application Publication No. 2003-127596 (FIG. 1) suggests an example in-mold transfer film used in such in-mold decorating. This in-mold transfer film has a mold-release layer on a surface of a base, and a printed ink layer provided on a surface of the mold-release layer by thermally transferring ink using a thermal transfer printer. Such formation of the printed ink layer is suitable for multi-kind and small-quantity production as compared with formation of a printed ink layer by a printing method, such as gravure printing, screen printing, or offset printing, or by depositing, with the use of a plate
FIG. 2 is an explanatory illustration showing procedures in sequence of in-mold decorating. As shown in part (a) of FIG. 2, a pair of molds 101A and 101B are opened, and an in-mold transfer film 102 is set at a predetermined position inside a mold 101 (the reference numeral 101 denotes a combination of the pair of molds 101A and 101B). At this time, the in-mold transfer film 102 is arranged such that a printed ink layer 102b provided on a base 102 faces a material to be injected to a cavity 101c (see part (b) of FIG. 2).
As shown in part (b) of FIG. 2, the mold 101 is clamped so that the mold 101 is closed. At this time, a predetermined portion of the in-mold transfer film 102 is sandwiched in the mold 101.
As shown in part (c) of FIG. 2, a material 103 is injected to the cavity 101c of the closed mold 101. The material 103 injected to the mold 101 is cooled and solidified to provide a molded part 104 as a transferred object. At this time, the material injected to the cavity 101c is injected to cover the printed ink layer 102b of the in-mold transfer film 102 arranged at the cavity 101c. The printed ink layer 102b contacting the material is bonded (thermally transferred) to a surface of the molded part 104 by heat and pressure (injection pressure) of the material.
As shown in part (d) of FIG. 2, the mold 101 is opened, and the molded part 104 is released from the cavity 101c of the mold 101. At this time, the portion of the printed ink layer 102b bonded to the molded part 104 is released from the base 102a of the in-mold transfer film 102.
As described above, in in-mold decorating, printing (decorating) is performed by transferring the printed ink layer 102a as an image applied to the molded part 104 during molding.
Meanwhile, in recent years, mold techniques and computer designs are becoming highly efficient. In the in-mold transfer film 102, the printed ink layer 102b as the image to be transferred to the transferred object 104 is also desired to be improved in shape followingness and graphical design.